OpenRaiser/Intern-Atlas huggingface dataset:
Analysing viewpoints in design through the argumentation process
Venue: arXiv cs.OH 2006
Year: 2006

We present an empirical study aimed at analysing the use of viewpoints in an industrial Concurrent Engineering context. Our focus is on the viewpoints expressed in the argumentative process taking place in evaluation meetings. Our results show that arguments enabling a viewpoint or proposal to be defended are often characterized by the use of constraints. Firstly, we show that, even if some constraints are apparently identically used by the different specialists involved in meetings, various meanings and weightings are associated with these constraints by these different specialists. Secondly, we show that the implicit or explicit nature of constraints depends on several interlocutive factors. Thirdly, we show that an argument often covers not only one constraint but a network of constraints. The type of combination reflects viewpoints which have specific status in the meeting. Then, we will propose a first model of the dynamics of viewpoints confrontation/integration.
Both Generic Design and Different Forms of Designing
Venue: arXiv cs.HC 2006
Year: 2006

This paper defends an augmented cognitively oriented "generic-design hypothesis": There are both significant similarities between the design activities implemented in different situations and crucial differences between these and other cognitive activities; yet, characteristics of a design situation (i.e., related to the designers, the artefact, and other task variables influencing these two) introduce specificities in the corresponding design activities and cognitive structures that are used. We thus combine the generic-design hypothesis with that of different "forms" of designing. In this paper, outlining a number of directions that need further elaboration, we propose a series of candidate dimensions underlying such forms of design.
Code Spectrum and Reliability Function: Binary Symmetric Channel
Venue: arXiv cs.IT 2006
Year: 2006

A new approach for upper bounding the channel reliability function using the code spectrum is described. It allows to treat in a unified way both a low and a high rate cases. In particular, the earlier known upper bounds are improved, and a new derivation of the sphere-packing bound is presented.
Least Significant Digit First Presburger Automata
Venue: arXiv cs.DS 2006
Year: 2006

Since 1969 \cite{C-MST69,S-SMJ77}, we know that any Presburger-definable set \cite{P-PCM29} (a set of integer vectors satisfying a formula in the first-order additive theory of the integers) can be represented by a state-based symmbolic representation, called in this paper Finite Digit Vector Automata (FDVA). Efficient algorithms for manipulating these sets have been recently developed. However, the problem of deciding if a FDVA represents such a set, is a well-known hard problem first solved by Muchnik in 1991 with a quadruply-exponential time algorithm. In this paper, we show how to determine in polynomial time whether a FDVA represents a Presburger-definable set, and we provide in this positive case a polynomial time algorithm that constructs a Presburger-formula that defines the same set.
The Workshop on Internet Topology (WIT) Report
Venue: arXiv cs.NI 2006
Year: 2006

Internet topology analysis has recently experienced a surge of interest in computer science, physics, and the mathematical sciences. However, researchers from these different disciplines tend to approach the same problem from different angles. As a result, the field of Internet topology analysis and modeling must untangle sets of inconsistent findings, conflicting claims, and contradicting statements. On May 10-12, 2006, CAIDA hosted the Workshop on Internet topology (WIT). By bringing together a group of researchers spanning the areas of computer science, physics, and the mathematical sciences, the workshop aimed to improve communication across these scientific disciplines, enable interdisciplinary crossfertilization, identify commonalities in the different approaches, promote synergy where it exists, and utilize the richness that results from exploring similar problems from multiple perspectives. This report describes the findings of the workshop, outlines a set of relevant open research problems identified by participants, and concludes with recommendations that can benefit all scientific communities interested in Internet topology research.
Social Networks and Social Information Filtering on Digg
Venue: arXiv cs.HC 2006
Year: 2006

The new social media sites -- blogs, wikis, Flickr and Digg, among others -- underscore the transformation of the Web to a participatory medium in which users are actively creating, evaluating and distributing information. Digg is a social news aggregator which allows users to submit links to, vote on and discuss news stories. Each day Digg selects a handful of stories to feature on its front page. Rather than rely on the opinion of a few editors, Digg aggregates opinions of thousands of its users to decide which stories to promote to the front page. Digg users can designate other users as ``friends'' and easily track friends' activities: what new stories they submitted, commented on or read. The friends interface acts as a \emph{social filtering} system, recommending to user stories his or her friends liked or found interesting. By tracking the votes received by newly submitted stories over time, we showed that social filtering is an effective information filtering approach. Specifically, we showed that (a) users tend to like stories submitted by friends and (b) users tend to like stories their friends read and liked. As a byproduct of social filtering, social networks also play a role in promoting stories to Digg's front page, potentially leading to ``tyranny of the minority'' situation where a disproportionate number of front page stories comes from the same small group of interconnected users. Despite this, social filtering is a promising new technology that can be used to personalize and tailor information to individual users: for example, through personal front pages.
Lightweight security mechanism for PSTN-VoIP cooperation
Venue: arXiv cs.CR 2006
Year: 2006

In this paper we describe a new, lightweight security mechanism for PSTN-VoIP cooperation that is based on two information hiding techniques: digital watermarking and steganography. Proposed scheme is especially suitable for PSTN-IP-PSTN (toll-by-passing) scenario which nowadays is very popular application of IP Telephony systems. With the use of this mechanism we authenticate end-to-end transmitted voice between PSTN users. Additionally we improve IP part traffic security (both media stream and VoIP signalling messages). Exemplary scenario is presented for SIP signalling protocol along with SIP-T extension and H.248/Megaco protocol.
Improving Precision of Type Analysis Using Non-Discriminative Union
Venue: arXiv cs.PL 2006
Year: 2006

This paper presents a new type analysis for logic programs. The analysis is performed with a priori type definitions; and type expressions are formed from a fixed alphabet of type constructors. Non-discriminative union is used to join type information from different sources without loss of precision. An operation that is performed repeatedly during an analysis is to detect if a fixpoint has been reached. This is reduced to checking the emptiness of types. Due to the use of non-discriminative union, the fundamental problem of checking the emptiness of types is more complex in the proposed type analysis than in other type analyses with a priori type definitions. The experimental results, however, show that use of tabling reduces the effect to a small fraction of analysis time on a set of benchmarks. Keywords: Type analysis, Non-discriminative union, Abstract interpretation, Tabling
Optimal Filtering for DDoS Attacks
Venue: arXiv cs.NI 2006
Year: 2006

Distributed Denial-of-Service (DDoS) attacks are a major problem in the Internet today. In one form of a DDoS attack, a large number of compromised hosts send unwanted traffic to the victim, thus exhausting the resources of the victim and preventing it from serving its legitimate clients. One of the main mechanisms that have been proposed to deal with DDoS is filtering, which allows routers to selectively block unwanted traffic. Given the magnitude of DDoS attacks and the high cost of filters in the routers today, the successful mitigation of a DDoS attack using filtering crucially depends on the efficient allocation of filtering resources. In this paper, we consider a single router, typically the gateway of the victim, with a limited number of available filters. We study how to optimally allocate filters to attack sources, or entire domains of attack sources, so as to maximize the amount of good traffic preserved, under a constraint on the number of filters. We formulate the problem as an optimization problem and solve it optimally using dynamic programming, study the properties of the optimal allocation, experiment with a simple heuristic and evaluate our solutions for a range of realistic attack-scenarios. First, we look at a single-tier where the collateral damage is high due to the filtering at the granularity of domains. Second, we look at the two-tier problem where we have an additional constraint on the number of filters and the filtering is performed on the granularity of attackers and domains.
Generalizations of the Hanoi Towers Problem
Venue: arXiv cs.DM 2006
Year: 2006

Our theme bases on the classical Hanoi Towers Problem. In this paper we will define a new problem, permitting some positions, that were not legal in the classical problem. Our goal is to find an optimal (shortest possible) sequence of discs' moves. Besides that, we will research all versions of 3-pegs classical problem with some special constraints, when some types of moves are disallowed.
Energy Efficient Randomized Communication in Unknown AdHoc Networks
Venue: arXiv cs.DC 2006
Year: 2006

This paper studies broadcasting and gossiping algorithms in random and general AdHoc networks. Our goal is not only to minimise the broadcasting and gossiping time, but also to minimise the energy consumption, which is measured in terms of the total number of messages (or transmissions) sent. We assume that the nodes of the network do not know the network, and that they can only send with a fixed power, meaning they can not adjust the areas sizes that their messages cover. We believe that under these circumstances the number of transmissions is a very good measure for the overall energy consumption. For random networks, we present a broadcasting algorithm where every node transmits at most once. We show that our algorithm broadcasts in $O(\log n)$ steps, w.h.p, where $n$ is the number of nodes. We then present a $O(d \log n)$ ($d$ is the expected degree) gossiping algorithm using $O(\log n)$ messages per node. For general networks with known diameter $D$, we present a randomised broadcasting algorithm with optimal broadcasting time $O(D \log (n/D) + \log^2 n)$ that uses an expected number of $O(\log^2 n / \log (n/D))$ transmissions per node. We also show a tradeoff result between the broadcasting time and the number of transmissions: we construct a network such that any oblivious algorithmusing a time-invariant distribution requires $Ω(\log^2 n / \log (n/D))$ messages per node in order to finish broadcasting in optimal time. This demonstrates the tightness of our upper bound. We also show that no oblivious algorithm can complete broadcasting w.h.p. using $o(\log n)$ messages per node.
A New Approach for Capacity Analysis of Large Dimensional Multi-Antenna Channels
Venue: arXiv cs.IT 2006
Year: 2006

This paper adresses the behaviour of the mutual information of correlated MIMO Rayleigh channels when the numbers of transmit and receive antennas converge to infinity at the same rate. Using a new and simple approach based on Poincaré-Nash inequality and on an integration by parts formula, it is rigorously established that the mutual information converges to a Gaussian random variable whose mean and variance are evaluated. These results confirm previous evaluations based on the powerful but non rigorous replica method. It is believed that the tools that are used in this paper are simple, robust, and of interest for the communications engineering community.
Developing efficient parsers in Prolog: the CLF manual (v1.0)
Venue: arXiv cs.SE 2006
Year: 2006

This document describes a couple of tools that help to quickly design and develop computer (formalized) languages. The first one use Flex to perform lexical analysis and the second is an extention of Prolog DCGs to perfom syntactical analysis. Initially designed as a new component for the Centaur system, these tools are now available independently and can be used to construct efficient Prolog parsers that can be integrated in Prolog or heterogeneous systems. This is the initial version of the CLF documentation. Updated version will be available online when necessary.
Achievable Rates for the General Gaussian Multiple Access Wire-Tap Channel with Collective Secrecy
Venue: arXiv cs.IT 2006
Year: 2006

We consider the General Gaussian Multiple Access Wire-Tap Channel (GGMAC-WT). In this scenario, multiple users communicate with an intended receiver in the presence of an intelligent and informed eavesdropper who is as capable as the intended receiver, but has different channel parameters. We aim to provide perfect secrecy for the transmitters in this multi-access environment. Using Gaussian codebooks, an achievable secrecy region is determined and the power allocation that maximizes the achievable sum-rate is found. Numerical results showing the new rate region are presented. It is shown that the multiple-access nature of the channel may be utilized to allow users with zero single-user secrecy capacity to be able to transmit in perfect secrecy. In addition, a new collaborative scheme is shown that may increase the achievable sum-rate. In this scheme, a user who would not transmit to maximize the sum rate can help another user who (i) has positive secrecy capacity to increase its rate, or (ii) has zero secrecy capacity to achieve a positive secrecy capacity.
A Calculus for Sensor Networks
Venue: arXiv cs.DC 2006
Year: 2006

We consider the problem of providing a rigorous model for programming wireless sensor networks. Assuming that collisions, packet losses, and errors are dealt with at the lower layers of the protocol stack, we propose a Calculus for Sensor Networks (CSN) that captures the main abstractions for programming applications for this class of devices. Besides providing the syntax and semantics for the calculus, we show its expressiveness by providing implementations for several examples of typical operations on sensor networks. Also included is a detailed discussion of possible extensions to CSN that enable the modeling of other important features of these networks such as sensor state, sampling strategies, and network security.
Error Exponents for Variable-length Block Codes with Feedback and Cost Constraints
Venue: arXiv cs.IT 2006
Year: 2006

Variable-length block-coding schemes are investigated for discrete memoryless channels with ideal feedback under cost constraints. Upper and lower bounds are found for the minimum achievable probability of decoding error $P_{e,\min}$ as a function of constraints $R, \AV$, and $\bar τ$ on the transmission rate, average cost, and average block length respectively. For given $R$ and $\AV$, the lower and upper bounds to the exponent $-(\ln P_{e,\min})/\bar τ$ are asymptotically equal as $\bar τ\to \infty$. The resulting reliability function, $\lim_{\bar τ\to \infty} (-\ln P_{e,\min})/\bar τ$, as a function of $R$ and $\AV$, is concave in the pair $(R, \AV)$ and generalizes the linear reliability function of Burnashev to include cost constraints. The results are generalized to a class of discrete-time memoryless channels with arbitrary alphabets, including additive Gaussian noise channels with amplitude and power constraints.
On Using Matching Theory to Understand P2P Network Design
Venue: arXiv cs.NI 2006
Year: 2006

This paper aims to provide insight into stability of collaboration choices in P2P networks. We study networks where exchanges between nodes are driven by the desire to receive the best service available. This is the case for most existing P2P networks. We explore an evolution model derived from stable roommates theory that accounts for heterogeneity between nodes. We show that most P2P applications can be modeled using stable matching theory. This is the case whenever preference lists can be deduced from the exchange policy. In many cases, the preferences lists are characterized by an interesting acyclic property. We show that P2P networks with acyclic preferences possess a unique stable state with good convergence properties.
Managing Query Compilation Memory Consumption to Improve DBMS Throughput
Venue: arXiv cs.DB 2006
Year: 2006

While there are known performance trade-offs between database page buffer pool and query execution memory allocation policies, little has been written on the impact of query compilation memory use on overall throughput of the database management system (DBMS). We present a new aspect of the query optimization problem and offer a solution implemented in Microsoft SQL Server 2005. The solution provides stable throughput for a range of workloads even when memory requests outstrip the ability of the hardware to service those requests.
The virtual reality framework for engineering objects
Venue: arXiv cs.CE 2006
Year: 2006

A framework for virtual reality of engineering objects has been developed. This framework may simulate different equipment related to virtual reality. Framework supports 6D dynamics, ordinary differential equations, finite formulas, vector and matrix operations. The framework also supports embedding of external software.
Accommodating Sample Size Effect on Similarity Measures in Speaker Clustering
Venue: arXiv cs.SD 2006
Year: 2006

We investigate the symmetric Kullback-Leibler (KL2) distance in speaker clustering and its unreported effects for differently-sized feature matrices. Speaker data is represented as Mel Frequency Cepstral Coefficient (MFCC) vectors, and features are compared using the KL2 metric to form clusters of speech segments for each speaker. We make two observations with respect to clustering based on KL2: 1.) The accuracy of clustering is strongly dependent on the absolute lengths of the speech segments and their extracted feature vectors. 2.) The accuracy of the similarity measure strongly degrades with the length of the shorter of the two speech segments. These effects of length can be attributed to the measure of covariance used in KL2. We demonstrate an empirical correction of this sample-size effect that increases clustering accuracy. We draw parallels to two Vector Quantization-based (VQ) similarity measures, one which exhibits an equivalent effect of sample size, and the second being less influenced by it.
Exact Failure Frequency Calculations for Extended Systems
Venue: arXiv cs.PF 2006
Year: 2006

This paper shows how the steady-state availability and failure frequency can be calculated in a single pass for very large systems, when the availability is expressed as a product of matrices. We apply the general procedure to $k$-out-of-$n$:G and linear consecutive $k$-out-of-$n$:F systems, and to a simple ladder network in which each edge and node may fail. We also give the associated generating functions when the components have identical availabilities and failure rates. For large systems, the failure rate of the whole system is asymptotically proportional to its size. This paves the way to ready-to-use formulae for various architectures, as well as proof that the differential operator approach to failure frequency calculations is very useful and straightforward.
On the Complexity of the Circular Chromatic Number
Venue: arXiv cs.CG 2006
Year: 2006

Circular chromatic number, $χ_c$ is a natural generalization of chromatic number. It is known that it is \NP-hard to determine whether or not an arbitrary graph $G$ satisfies $χ(G) = χ_c(G)$. In this paper we prove that this problem is \NP-hard even if the chromatic number of the graph is known. This answers a question of Xuding Zhu. Also we prove that for all positive integers $k \ge 2$ and $n \ge 3$, for a given graph $G$ with $χ(G)=n$, it is \NP-complete to verify if $χ_c(G) \le n- \frac{1}{k}$.
Intelligent location of simultaneously active acoustic emission sources: Part I
Venue: arXiv cs.NE 2007
Year: 2007

The intelligent acoustic emission locator is described in Part I, while Part II discusses blind source separation, time delay estimation and location of two simultaneously active continuous acoustic emission sources. The location of acoustic emission on complicated aircraft frame structures is a difficult problem of non-destructive testing. This article describes an intelligent acoustic emission source locator. The intelligent locator comprises a sensor antenna and a general regression neural network, which solves the location problem based on learning from examples. Locator performance was tested on different test specimens. Tests have shown that the accuracy of location depends on sound velocity and attenuation in the specimen, the dimensions of the tested area, and the properties of stored data. The location accuracy achieved by the intelligent locator is comparable to that obtained by the conventional triangulation method, while the applicability of the intelligent locator is more general since analysis of sonic ray paths is avoided. This is a promising method for non-destructive testing of aircraft frame structures by the acoustic emission method.
Real Options for Project Schedules (ROPS)
Venue: arXiv cs.CE 2007
Year: 2007

Real Options for Project Schedules (ROPS) has three recursive sampling/optimization shells. An outer Adaptive Simulated Annealing (ASA) optimization shell optimizes parameters of strategic Plans containing multiple Projects containing ordered Tasks. A middle shell samples probability distributions of durations of Tasks. An inner shell samples probability distributions of costs of Tasks. PATHTREE is used to develop options on schedules.. Algorithms used for Trading in Risk Dimensions (TRD) are applied to develop a relative risk analysis among projects.
Pseudo-random Puncturing: A Technique to Lower the Error Floor of Turbo Codes
Venue: arXiv cs.IT 2007
Year: 2007

It has been observed that particular rate-1/2 partially systematic parallel concatenated convolutional codes (PCCCs) can achieve a lower error floor than that of their rate-1/3 parent codes. Nevertheless, good puncturing patterns can only be identified by means of an exhaustive search, whilst convergence towards low bit error probabilities can be problematic when the systematic output of a rate-1/2 partially systematic PCCC is heavily punctured. In this paper, we present and study a family of rate-1/2 partially systematic PCCCs, which we call pseudo-randomly punctured codes. We evaluate their bit error rate performance and we show that they always yield a lower error floor than that of their rate-1/3 parent codes. Furthermore, we compare analytic results to simulations and we demonstrate that their performance converges towards the error floor region, owning to the moderate puncturing of their systematic output. Consequently, we propose pseudo-random puncturing as a means of improving the bandwidth efficiency of a PCCC and simultaneously lowering its error floor.